1. Field of the Invention
The present invention is related to a coupling lock, and more particularly, to a lock that firmly secures together a base and cover without any fixing member.
2. Description of the Prior Art
A prior art of a coupling lock, e.g. that used to lock up a bike, is comprised of a base, an accommodation chamber provided in the base, and a keyway extending outwardly from and connected through said chamber to permit the insertion of a key. A block in said chamber is provided at its front end with multiple channels arranged in a single row, having a pin respectively provided in each of said channels. A lever protrudes outwardly from said block and is connected to a plunger at the other end of said lever and in parallel to said block. One end of said plunger fits into a recess in the lever, while the other end freely fits into the base so as to allow the insertion of a correct key tab. A plurality of holes on the key tab respectively match with corresponding pins to allow the pins to disengage from the channels for the block to move inward, in turn the plunger also moves to unlock by releasing the locking lever. Furthermore, a matching cover is provided above the base and both are provided with holes to accept the insertion of a screw, which fixes together the base and the cover. However, the prior art coupling lock has the following defectives:
1. Relying upon the locking by the screw to tightly incorporate the base and the cover not only makes the assembling sophisticated but also is vulnerable to falling apart due to the loosening of the screw from the locking hole.
2. The single row arrangement of the channels on the block allows only variance in quantity. As a result, the combination can be easily broken.